Device for plane cutting the surfaces of moulded blocks of lightweight concrete or similar material



Dec. 23. 1969 P. JA'KOBSSON E L 3 8 DEVICE FOR PLANE CUTTING THE SURFACES OF MOULDED BLOCKS OF LIGHTWEIGHT CONCRETE OR SIMILAR MATERIAL Filed Oct. 25, 1967 uvvENmRs PER mggoassow STIG LONNBERG ATTORNEYS United States Patent 3,484,913 DEVICE FOR PLANE CUTTING THE SURFACES OF MOULDED BLOCKS OF LIGHTWEIGHT CON- CRETE OR SIMILAR MATERIAL Per Jakobsson, Blombergsvagen 24, Orebro, Sweden, and Stig Lonnberg, Tradgardsgatan 17, Kumla, Sweden Filed Oct. 25, 1967, Ser. No. 677,944 Claims priority, application Sweden, Nov. 4, 1966, 15,126/ 66 Int. Cl. B28b 11/14 US. Cl. 25-110 4 Claims ABSTRACT OF THE DISCLOSURE A rotary wire-type plane cutter for moulded blocks of lightweight concrete comprising a number of supporting plates mounted on a shaft at spaced intervals to form a series of compartments. The cutting wires are stretched over the supporting plates in an arrangement wherein each of the wires alternately extend in a straight unbroken line between the supporting plates forming one compartment but are drawn inwardly toward the shaft while passing over the supporting plates forming the next compartment.

FIELD OF THE INVENTION The present invention relates to cutting devices and more particularly to devices for plane cutting the surfaces of moulded blocks of lightweight concrete or similar material.

BACKGROUND OF THE INVENTION AND THE PRIOR ART A number of cutting devices have been used in the removal of excess material produced in the casting of a raw mixture of lightweight concrete. One such device comprises a plurality of circular supporting plates fixed on a shaft at suitable distances from each other with the two outermost supporting plates dimensioned so that cutting wires can be stretched over them. This prior art device is combined with a screw conveyer and includes inner supporting plates which serve as intermediate supports for and to prevent dislocation of the cutting wires. The cutting wires themselves are firmly fixed at the hub of one of the outermost supporting plates and extend through outlets in the periphery of the plate to the second outermost supporting plate. The cutting wires are attached to the hub of the second supporting plates through springs and may be tightened to vary the tension thereon.

This particular form of wire cutter is generally superior to other known prior art devices used for the same purpose but it is still subject to certain disadvantages. Chief among these disadvantages is the problem of occasional wire breakage. Wire breakage results in, first, rejection of the portion of the moulded block being cut during the time the breakage occurs and secondly, stoppage of the cutting process for the rather substantial length of time required for removal of the broken wire and the substitution of a new wire. It is apparent that if wire breakages occur often the cutting device cannot be successfully utilized in a production line process in which each work operation must be performed within a predetermined amount of time.

BRIEF SUMMARY OF THE INVENTION In accordance with the present invention a cutting device is provided wherein the abovementioned disadvantages are substantially eliminated, In accordance with a presently preferred embodiment of the invention cutting wires are suspended over a plurality of support members which taken two at a time form a series of compartments.

The cutting wires are arranged to alternately extend in an unbroken line between support plates forming one compartment while being drawn down inwardly toward the shaft mounting the supporting plates while passing over the supporting plates forming the next compartment. This arrangement ensures that the cutting wires will remain in a fixed position against the supportnig plates thereby precluding a characteristic sliding movement of the wires against the supporting plates. This sliding movement causes rubbing and Wear of the wires and ultimately breakage thereof.

Other features and objects of the present invention will become apparent upon consideration of the following detailed description of the drawings in which:

FIG. 1 is a top view of the cutting; device in accordance with a presently preferred embodiment of the invention,

FIG. 2 is an end view of the cutting device of FIG. 1, and

FIG. 3 is a sectional view taken along lines AA in FIG. 1.

Referring to FIG. 1 a wire cutter 10 is shown which comprises a shaft 11 fixedly mounting a number of circular supporting plates 12. Plates 12 are equally spaced along the length of the shaft and divide the shaft into a series of compartments 13 to 17. A plurality of cutting wires, five of which denoted 18 through 22 are shown in FIG. 1, are stretched over the. supporting plates 12 between hubs 23 and 24 located on shaft 11, Cutting wires 18 to 22 are firmly fixed at hub 23 and are attached to opposite hub 24 via springs 25. Wires 18 to 22 may be tightened at hub 24 to adjust the tensioning on the wires.

The cutting wires of cutting devices like that previously described are stretched between the first and second outermost plates in a straight, unbroken line. In accordance with the present invention each of the cutting wires 18 to 22 are arranged to extend in a straight, unbroken line between support plates forming one compartment but are drawn inwardly toward shaft 11 while passing over the support plates forming the next compartment. The drawing or pulley of the wires 18 to 22 toward shaft 11 is accomplished through the use of circular fastening plates 26 which are fixed on the shaft 11 at locations intermediate to the supporting plates 12. Hooks 27 are located on the periphery of the fastening plates 26 for securing the wires 18 to 22 to the fastening plates 26. As can best be seen in FIG. 3 hooks 27 are located in positions about the periphery of fastening plates 26 corresponding to the positions at which the wires 18 to 22 are fastened to the hubs 23, 24.

As stated, the cutting wires 18 to .22 are alternately drawn in toward shaft 11 and straight stretched. For example, wire 18 extends between the supporting plates 12 in a straight, unbroken line parallel to shaft 11 for compartment 17 but is drawn in toward shaft 11 and secured to fastening plate 26 for the adjacent compartment 16. In this way the cutting surface of the plane cutter of the invention is provided with an even distribution of the active cutting wires.

As shown in FIG. 1, the cutting wires are alternately straight extending and drawn in, proceeding around the periphery of the cutting device 10. For example, referring to compartment 17, wire 18 is straight, wire 19 is drawn, in, wire 20 is straight, wire 21 is drawn in, and wire 22 is straight. This sequence would, of course, continue throughout the periphery of the cutting device 10,

The plane cutter of the present invention produces a process surface on the moulded block which is completely plain and which shows fully open pores. These good results appear to be the result of the fact that the wires 18 to 22 of the cutter 10 remain in a fixed position against the supporting plates 12 during the cutting operation. In contrast, the cutting wires of the prior art cutter previously described are stretched over the entire length of the cutter and are caused to bend by the pressure of the lightweight concrete mass during the cutting operation. When cutting is terminated the cutting wires will return to their original position and thus the wires undergo a sliding movement against the supporting plates during each rotational turn of the cutter. This sliding movement causes rubbing and wear of the cutting wires and ultimately breakage thereof. For example, the cutting wires might extend in a straight line between two end supporting plates 12 of FIG. 1 and thus the wires would rub against these plates as well as against any intermediate supporting plates. The arrangement of the wires in accordance with the present invention substantially precludes such sliding motion and thus breakage caused thereby. By arranging the cutting wires into short sections the lengths of cutting surface areas in contact with the mould are greatly reduced as compared with simple straight wires arranged as previously described and thus the amount of bending and sliding of the cutting wires is correspondingly reduced.

It will be understood by those skilled in the art that the embodiment of the invention shown and described herein is subject to various modifications without departing from the scope and spirit of the invention. For example; the cutting wires may be drawn or pulled toward the shaft with bands rather than with the fastening plates 26 including hoods 27 as shown. Accordingly, it should be understood that the invention is not limited by the exemplary embodiments shown and described but rather only by the subjoined claims as construed in light of the foregoing specification and drawings.

Having thus described our invention in accordance with the patent statutes,

We claim:

1. A cutting device comprising a shaft, a plurality of supporting plates mounted on said shaft at spaced distances from one another along the length of said shaft to thereby divide said cutting device into a series of compartments, and a plurality of cutting wires stretched over said supporting plates, each of said cutting wires alternately extending in an unbroken line between support plates forming one compartment while being drawn inwardly toward the shaft while passing over the support plates forming the next compartment.

2. A cutting device in accordance with claim 1, wherein said plurality of cutting wires are arranged about the periphery of said supporting plates, said cutting wires being alternately straight stretched and drawn toward the shaft around said periphery.

3. A cutting device in accordance with claim 1, wherein each of said cutting wires drawn inwardly toward the shaft are further supported at a point inwardly of the outer diameter of said support plates at a location intermediate to the plates forming the compartment.

4. A cutting device in accordance with claim 3 further comprising circular fastening plates provided with hooks about the periphery thereof for securing said cutting wires at points inwardly of the outer diameter of said support plates.

References Cited UNITED STATES PATENTS 2,896,298 7/1959 Olsson 25104 FOREIGN PATENTS 540,264 4/1957 Canada.

I. SPENCER OVERHOLSER, Primary Examiner MICHAEL O. SUTTON, Assistant Examiner US. Cl. X.R. 25104 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION ent No. & Dated December 23, 1969 entor(s) Per Jakobsson and Stig Lonnber' It is certified that error appears in the above-identified patent that said Letters Patent are hereby corrected as shown below:

Column 1, line 6, after "Kumla, Sweden" insert:

, assignor's to Intong Aktiebolag, Hallabrottet,

Sweden SIGNED AND SEALED OCT 27 .1970

iEAL) new amt-1m saw. an. g Officer fiomissionar of Patents USCOMM-DC 603764 69 a u.s. eovnunnn rnmmac OFFICE: I!!! o-su-su 

